Answer
Cobicistat (Tybost) is a CYP3A inhibitor. As a single agent, it is indicated to increase systemic exposure of atazanavir or darunavir (once-daily dosing regimen) in combination with other antiretroviral agents. These indications are weight-dependent in adolescents (ie, use with atazanavir in adolescents weighing at least 35 kg or with darunavir in those weighing at least 40 kg).
Cobicistat may be used for treatment-naïve or treatment-experienced patients (without darunavir resistance–associated substitutions). The dosage is 150 mg PO once daily plus atazanavir 300 mg PO once daily or darunavir 800 mg PO once daily.
It is also a component of elvitegravir/cobicistat/emtricitabine/tenofovir DF (Stribild), elvitegravir/cobicistat/emtricitabine/tenofovir AF (Genvoya), darunavir/cobicistat (Prezcobix), and atazanavir/cobicistat (Evotaz).
Use in patients aged 12 years or older has been approved for the combination products elvitegravir/cobicistat/emtricitabine/tenofovir (Stribild, Genvoya).